Chromothripsis followed by circular recombination drives oncogene amplification in human cancer

The mechanisms behind the evolution of complex genomic amplifications in cancer have remained largely unclear. Using whole-genome sequencing data of the pediatric tumor neuroblastoma, we here identified a type of amplification, termed 'seismic amplification', that is characterized by multiple rearrangements and discontinuous copy number levels. Overall, seismic amplifications occurred in 9.9% (274 of 2,756) of cases across 38 cancer types, and were associated with massively increased copy numbers and elevated oncogene expression. Reconstruction of the development of seismic amplification showed a stepwise evolution, starting with a chromothripsis event, followed by formation of circular extrachromosomal DNA that subsequently underwent repetitive rounds of circular recombination. The resulting amplicons persisted as extrachromosomal DNA circles or had reintegrated into the genome in overt tumors. Together, our data indicate that the sequential occurrence of chromothripsis and circular recombination drives oncogene amplification and overexpression in a substantial fraction of human malignancies.

Telomerase Is a Prognostic Marker of Poor Outcome and a Therapeutic Target in Neuroblastoma

PURPOSE

Telomere maintenance is a hallmark of high-risk neuroblastoma; however, the contribution of telomerase and alternative lengthening of telomeres (ALT) to clinical phenotypes has remained unclear. We aimed to determine the clinical relevance of telomerase activation versus ALT as biomarkers in pretreatment neuroblastoma and to assess the potential value of telomerase as a therapeutic target.

MATERIALS AND METHODS

The genomic status of TERT and MYCN was assessed in 457 pretreatment neuroblastomas by fluorescence in situ hybridization. ALT was examined in 273 of 457 tumors by detection of ALT-associated promyelocytic leukemia nuclear bodies, and TERT expression was determined by microarrays in 223 of these. Cytotoxic effects of telomerase-interacting compounds were analyzed in neuroblastoma cell lines in vitro and in vivo.

RESULTS

We detected TERT rearrangements in 46 of 457 cases (10.1%), MYCN amplification in 93 of 457 cases (20.4%), and elevated TERT expression in tumors lacking TERT or MYCN alterations in 10 of 223 cases (4.5%). ALT activation was found in 49 of 273 cases (17.9%). All these alterations occurred almost mutually exclusively and were associated with unfavorable prognostic variables and adverse outcome. The presence of activated telomerase (ie, TERT rearrangements, MYCN amplification, or high TERT expression without these alterations) was associated with poorest overall survival and was an independent prognostic marker in multivariable analyses. We also found that the telomerase-interacting compound 6-thio-2'-deoxyguanosine effectively inhibited viability and proliferation of neuroblastoma cells bearing activated telomerase. Similarly, tumor growth was strongly impaired upon 6-thio-2'-deoxyguanosine treatment in telomerase-positive neuroblastoma xenografts in mice.

CONCLUSION

Our data suggest telomerase activation and ALT define distinct neuroblastoma subgroups with adverse outcome and that telomerase may represent a promising therapeutic target in many high-risk neuroblastomas.

A mechanistic classification of clinical phenotypes in neuroblastoma

Neuroblastoma is a pediatric tumor of the sympathetic nervous system. Its clinical course ranges from spontaneous tumor regression to fatal progression. To investigate the molecular features of the divergent tumor subtypes, we performed genome sequencing on 416 pretreatment neuroblastomas and assessed telomere maintenance mechanisms in 208 of these tumors. We found that patients whose tumors lacked telomere maintenance mechanisms had an excellent prognosis, whereas the prognosis of patients whose tumors harbored telomere maintenance mechanisms was substantially worse. Survival rates were lowest for neuroblastoma patients whose tumors harbored telomere maintenance mechanisms in combination with RAS and/or p53 pathway mutations. Spontaneous tumor regression occurred both in the presence and absence of these mutations in patients with telomere maintenance-negative tumors. On the basis of these data, we propose a mechanistic classification of neuroblastoma that may benefit the clinical management of patients.

Quality of life in schizophrenia and bipolar disorder: The impact of symptomatic remission and resilience

BACKGROUND

Health-related quality of life (HRQOL) is significantly affected in individuals with schizophrenia or bipolar I disorder (BD-I). The current study investigated whether symptomatic remission and resilience might differently impact HRQOL in these patients.

METHODS

Fifty-two patients with schizophrenia and 60 patients suffering from BD-I from outpatient mental health services as well as 77 healthy control subjects from the general community were included into a cross-sectional study. HRQOL and resilience were assessed using the WHOQOL-BREF and the Resilience Scale. In patients, psychopathology was quantified by the Positive and Negative Syndrome Scale or the Montgomery Asberg Depression Rating Scale and the Young Mania Rating Scale, respectively.

RESULTS

Notably, both patient groups showed lower HRQOL and resilience compared to control subjects, non-remitted patients indicated lower HRQOL than remitted ones. The effect of remission on HRQOL was significantly larger in patients with BD-I than in those with schizophrenia but did not explain the difference in HRQOL between groups. Resilience predicted HRQOL in all three groups. When accounting for the effect of resilience among remitted patients, only the difference in HRQOL between schizophrenia patients and control subjects was significant.

CONCLUSION

These findings demonstrate the impact of symptomatic remission and resilience on HRQOL of both patients suffering from schizophrenia and BD-I and indicate that these factors are especially relevant for HRQOL of patients with BD-I.

Quality of life in stabilized patients with schizophrenia is mainly associated with resilience and self-esteem

OBJECTIVE

Improving quality of life (QoL) is an important objective in the treatment of schizophrenia. The aim of the current study was to examine to what extent resilience, self-esteem, hopelessness, and psychopathology are correlated with QoL.

METHOD

We recruited 52 out-patients diagnosed with schizophrenia according to DSM-IV criteria and 77 healthy control subjects from the general community. In patients, psychopathology was quantified by the Positive and Negative Syndrome Scale. The following scales were used in both patients and control subjects: the Berliner Lebensqualitätsprofil, the Resilience Scale, the Rosenberg Self-Esteem Scale, and the Beck Hopelessness Scale to assess QoL, resilience, self-esteem, and hopelessness respectively.

RESULTS

Patients with schizophrenia presented with significantly less QoL, resilience, self-esteem, and hope compared to healthy control subjects. In patients, QoL correlated moderately with resilience, self-esteem, and hopelessness and weakly with symptoms. With respect to the latter, particularly depression and positive symptoms were negatively correlated with QoL.

CONCLUSION

Our results highlight the complex nature of QoL in patients suffering from schizophrenia. They underscore that significant efforts are necessary to enhance resilience and self-esteem and to diminish hopelessness as well as affective and positive symptoms in patients with schizophrenia.

Using tests for recent infection to estimate incidence: problems and prospects for HIV

Tests for recent infection (TRIs), such as the BED assay, provide a convenient way to estimate HIV incidence rates from cross-sectional survey data. Controversy has arisen over how the imperfect performance of a TRI should be characterised and taken into account. Recent theoretical work is providing a unified framework within which to work with a variety of TRI- and epidemic-specific assumptions in order to estimate incidence using imperfect TRIs, but suggests that larger survey sample sizes will be required than previously thought. This paper reviews the framework qualitatively and provides examples of estimator performance, identifying the characteristics required by a TRI to estimate incidence reliably that should guide the future development of TRIs.

Using tests for recent infection to estimate incidence: problems and prospects for HIV

Tests for recent infection (TRIs), such as the BED assay, provide a convenient way to estimate HIV incidence rates from cross-sectional survey data. Controversy has arisen over how the imperfect performance of a TRI should be characterised and taken into account. Recent theoretical work is providing a unified framework within which to work with a variety of TRI- and epidemic-specific assumptions in order to estimate incidence using imperfect TRIs, but suggests that larger survey sample sizes will be required than previously thought. This paper reviews the framework qualitatively and provides examples of estimator performance, identifying the characteristics required by a TRI to estimate incidence reliably that should guide the future development of TRIs.